MANKATO, Minn. -- I was all but amazed to see Minnesota Vikings linebacker E.J. Henderson take every first-team repetition during a hard practice in humid weather Monday morning, and we'll soon be discussing what might be the most unexpected story in the NFC North. First, however, let's get to the interesting scenario that continued playing out among the Vikings' defensive backs during my first practice at Minnesota State, Mankato.

In a team drill that mostly featured the nickel defense, the Vikings were using rookie Chris Cook as the left cornerback and second-year player Asher Allen on the right. As usual, Antoine Winfield was inside playing the slot receiver. Lito Sheppard, the veteran signed as a short-term replacement for injured starter Cedric Griffin, was relegated to the second team.

It's awfully early to start writing a depth chart in pencil, let alone with pen or in stone. But based on what I saw, I'm thinking the Vikings will be thrilled if either Cook or Allen wins the starting right cornerback job. (Winfield plays the left side in base sets.) While Sheppard certainly knows all of the veteran tricks, let's just say there is a reason why he was available days before the draft for a relatively modest $2 million.

I didn't hold anything against Sheppard when receiver Bernard Berrian ran past him on the right sideline. Berrian does that to plenty of cornerbacks. But when second- and third-team receivers start running past you -- and remember, the Vikings' second- and third-teamers are really their third-and-fourth teamers because of the absences of Sidney Rice and Percy Harvin -- then it's worth considering other options.

Cook has rapidly ascended to the top of that list, and not just because he was the Vikings' top pick in the April draft. He started grabbing attention last week with a three-interception practice, and Monday's assignment represented a notable move up the depth chart.

"Things are going pretty good," Cook said. "The game is starting to slow down a little bit. I feel pretty good going into the second week."

The next step would be for Cook to start getting work on the right side, where he played during his senior year at Virginia.

"Nothing says he can't got to right," coach Brad Childress said. "We're just letting him settle there on the left side. When you're working on the left side, with a right-handed quarterback, you're getting more looks there anyway."

At 6-foot-2 and 212 pounds, Cook has a similar build to Green Bay Packers cornerback Al Harris. I won't even suggest Cook has the same coverage skills at this point, but he's an excellent fit for a team that typically asks its cornerbacks to redirect receivers at the line of scrimmage when it plays its Cover 2 scheme.

Defensive coordinator Leslie Frazier said Cook "seems to be handling things very well" but will reserve judgment on his immediate future until he gets a sense for his game-day mentality. The Vikings open their preseason Saturday at St. Louis. Expect Cook to see plenty of work, with perhaps the first and definitely second teams.

On a related subject, let's address a question I've heard often on this summer's NFC North training camp tour. Monday morning at least, I saw no residual evidence of the foot fracture that limited Winfield last season. Neither has Childress.

"Antoine has come back full speed," Childress said. "There is no grab or hesitation. He can stick the foot in the ground and go."

Ok, I'll have some Day 1 observations for you after the Vikings' second practice.